This is an integrated program of research into the immune response of primary tumor-hosts to the antigens of their own tumors. The program includes studies of human tumors and of experimentally induced tumors of mice. The ultimate objectives of the program are to develop and evaluate effective techniques for the immunotherapy of cancer and for its early detection. Human studies will concentrate on tumors of the breast, prostate and lung. Cell-mediated immunity (CMI), serum blocking factor (SBF) and unblocking factor (UBF) will be measured in cancer patients and correlations sought with disease status, treatment, prognosis and recurrence. CMI and UBF specific for individual tumor types will be sought in individuals having non-malignant hyperplasia of the corresponding tissue. The animal system is that of Rous sarcomas in mice. Primary tumor-hosts generated through a study of genetic factors influencing susceptibility to RSV will be studied by in vivo and in vitro methods for analysis of their immune response to tumor specific antigens. These parallel studies are intended to shed light on the biological significance of the in vitro measurements. Primary tumor-hosts will be treated and manipulated in ways calculated to disturb the balance of the immune response. These manipulations will be studied for their effect on tumor growth and on the immune response as measured in vitro. UBF specific for murine Rous sarcoma will be produced by deliberate immunization and tested for efficacy in vitro by the microcytotoxicity test and in vivo by administration to mice carrying Rous sarcoma. Modern techniques of immunochemistry will be applied to the purification and characterization of human and murine SBF and UBF. The interaction between SBF and UBF will be studied. Purified SBF will be radio-labelled in an attempt to develop a radio-immunoassay for circulating SBF.